You mention WordPress, and I'm trying to figure out if you're creating
your own "ecommerce" system, or using a plugin? Even if you use a
plugin, you can direct it to the PayPal development account (for testing).
I would think that a WordPress plugin would be using PayPal Express Checkout.
But you can create your own system if not using a plugin. And you won't be
using PayPal buttons.
This is where you can test everything using a fake buyer and fake seller. All
transactions look and operate like real, but they are not real. The site also has
a lot of documentation and scripting examples on using PayPal API for your
So you'll see that you won't be using PayPal buttons at all.
You may decide to use PayPal Express Checkout ... where you can
build your own product lists with as many options as you want:
You use the developer site to fully develop and test your website, just like
the real thing. You purchase things from your site using a fake credit card number.
After everything is fully tested, you simply point all of the PayPal account
configuration (seller account) to your REAL PayPal account.